Piston-valve engagement in fluid sprayers

ABSTRACT

A pump draws fluid from a reservoir and drives the fluid downstream to a spray tip where the fluid is applied to a surface. A piston is driven in a reciprocating manner to pump the fluid. A check valve is disposed downstream of the piston to regulate a flow of the fluid downstream from the piston. The pump is initially dry and is primed with fluid prior to operation. To facilitate priming, the piston is dimensioned to impact the ball and unseat a valve member of the check valve during a priming stroke, thereby ejecting any air from the pump through the check valve. With the air ejected from the pump, a vacuum is formed during a suction stroke of the piston, which draws fluid downstream from the reservoir to prime the pump.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims priority to U.S. Provisional Application No.62/394,624 filed Sep. 14, 2016, and entitled “PISTON-VALVE ENGAGEMENT INFLUID SPRAYERS,” the disclosure of which is hereby incorporated in itsentirety.

BACKGROUND

This disclosure generally relates to fluid sprayers. More particularly,this disclosure relates to fluid sprayer pumps.

Sprayers pull fluid from a fluid source and apply the fluid to a surfacethrough a nozzle. The sprayer includes a pump that pulls the fluid fromthe fluid source and drives the fluid downstream to the nozzle. Prior tooperating the sprayer, the pump is dry and must be primed. When the pumpis dry, air is disposed within pump cylinders between the check valvesand the pistons, which hinders the proper uptake of fluid by the pump.The piston can compress the air, but the air pressure can beinsufficient to overcome the force maintaining the check valve in theclosed position, such as surface tension of sticky residue from aprevious use. When the check valve is stuck in the closed position, auser removes the check valve from the pump and manually manipulates thecheck valve so air can be ejected through the check valve duringpriming.

SUMMARY

According to an aspect of the disclosure, a pump includes a first pistondisposed within a first axial bore of a pump body and a first checkvalve disposed at an exit of the first axial bore. The first piston hasa downstream end movable within the first axial bore. The first checkvalve includes a first valve member. The downstream end of the firstpiston is configured to impact the first valve member to drive the firstvalve member from a closed position to an open position.

According to another aspect of the disclosure, a sprayer includes asprayer body, a spray tip attached to the sprayer body and configured tospray a fluid, a reservoir connected to the sprayer body and configuredto store a supply of the fluid, and a pump disposed within the sprayerbody and configured to draw the fluid from the reservoir and drive thefluid downstream to the spray tip. The pump includes a pump body mountedwithin the sprayer body, a piston, and a check valve. The pump bodyincludes an axial bore and an inlet channel configured to fluidlyconnect the axial bore and the reservoir. The piston extends into theaxial bore and has a downstream end configured to reciprocate within theaxial bore. The check valve is disposed within the axial bore downstreamof the piston and includes a valve member. The downstream end of thepiston is configured to impact the valve member to drive the valvemember from a closed position to an open position.

According to yet another aspect of the disclosure, a method of priming apump includes driving a piston through a priming stroke; impacting avalve member with the piston to drive the valve member from a closedposition to an open position; and pulling the piston through a suctionstoke.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is an isometric view of a sprayer.

FIG. 1B is a cross-sectional view of a sprayer taken along line B-B inFIG. 1A.

FIG. 2A is a front isometric view of a drive assembly for a sprayer.

FIG. 2B is a rear isometric view of a drive assembly for a sprayer.

FIG. 3A is a cross-sectional view of a drive assembly for a sprayertaken along line A-A in FIG. 2A.

FIG. 3B is a cross-sectional view of a drive assembly for a sprayertaken along line B-B in FIG. 2A.

FIG. 3C is an enhanced view of detail Z in FIG. 3B.

FIG. 4A is an isometric view of a check valve.

FIG. 4B is an exploded view of a check valve.

FIG. 5 is a flowchart of a method of priming a pump.

DETAILED DESCRIPTION

Sprayers according to the present disclosure spray various fluids,examples of which include paint, water, oil, stains, finishes,aggregate, coatings, and solvents, among other options, onto a surface.In some examples, the sprayer is a handheld sprayer for fluids such aspaint, varnish, water, oil, stains, finishes, coatings, and solvents,among others. In some examples, the sprayer can be a sprayer for a fixedindustrial installation or automatic device.

FIG. 1A is a perspective view of sprayer 10. FIG. 1B is across-sectional view of sprayer 10 taken along line B-B in FIG. 1A.FIGS. 1A and 1B will be discussed together. Sprayer 10 includes housing12, handle 13, reservoir 14, spray tip 16, motor 18, and pump 20. Spraytip 16 includes nozzle 22 and exit channel 24. Pump 20 includes pumpbody 26, drive 28, piston 30, check valve 32, cylinder 34, and seal 36.Pump body 26 includes cylinder housing 38, axial bore 40, radial bore42, and intake channel 44. Drive 28 includes gear 46 and wobble (orswash) plate 48. Piston 30 includes upstream end 50 and downstream end52. Check valve 32 includes cage 54, ball 56, and spring 58.

Reservoir 14 is mounted to housing 12 and configured to store a supplyof fluid to be sprayed. Reservoir 14 can include a flexible polymercontainer within which the fluid is stored. While reservoir 14 ismounted to housing 12, it is understood that reservoir 14 can be remotefrom housing 12 and can provide fluid through a fluid line. Handle 13 isattached to housing 12 and can be integrally formed with housing 12.Handle 13 allows a user to operate sprayer 10 with a single hand. Spraytip 16 is disposed within housing 12. Nozzle 22 is disposed at adownstream end of spray tip 16 and is configured to spray fluid receivedfrom reservoir 14 onto a surface to be coated. Pump 20 is disposed inhousing 12 between reservoir 14 and spray tip 16 and is configured todraw fluid from reservoir 14 and supply fluid to nozzle 22 through exitchannel 24. Housing 12 can be of any suitable configuration forcontaining the various components of sprayer 10, such as a moldedpolymer clamshell.

Pump 20 is disposed within housing 12 and configure to draw fluid fromreservoir 14 and drive the fluid downstream to nozzle 22. Pump body 26is at least partially disposed within housing 12 and defines a flowpathfor the fluid to flow between reservoir 14 and spray tip 16. Cylinderhousing 38 forms a portion of pump body 26. Axial bore 40 extendsthrough pump body 26 and cylinder housing 38, and cylinder 34 isdisposed in axial bore 40 within cylinder housing 38. Intake channel 44extends through pump body 26 between reservoir 14 and cylinder 34. Seal36 is disposed at an upstream end of axial bore 40 and prevents fluidfrom leaking out of the upstream end of axial bore 40. In some examples,seal 36 can be a u-cup seal containing a pre-rolled o-ring. Radial bore42 extends through pump body 26 and fluidly connects axial bore 40 withadditional axial bores (discussed in detail in FIGS. 3A-3B) such thatfluid supplied to any axial bore can flow to exit channel 24 and nozzle22. Pump body 26 can be a polymeric structure and can be formed, forexample, by injection molding. Axial bore 40, radial bore 42, and intakechannel 44 can be formed by a mechanical removal process, such asdrilling or machining. In some examples, pump body 26 can be formedthrough an additive manufacturing process such that axial bore 40,radial bore 42, and intake channel 44 are integrally formed in pump body26.

Drive 28 is disposed within housing 12 and supported by housing 12 andpump body 26. Motor 18 is disposed in housing 12 and provides rotationalpower to drive 28. In some examples, motor 18 can be an electric motor,such as a brushed electric motor, a gas motor, or a pneumatic motor,among others. Gear 46 interfaces with and is directly driven by motor18. In some examples, motor 18 is connected to gear 46 by interfacinggear teeth, but it is understood that motor 18 and gear 46 can beconnected in any suitable manner, such as by a belt or chain. Wobbleplate 48 is connected to and powered by gear 46, and wobble plate 48converts the rotational movement of gear 46 into linear motion of piston30. Drive 28 is thus configured to convert the rotational movement ofmotor 18 to linear, reciprocal motion of piston 30. While drive 28 isdescribed as including gear 46 and wobble plate 48, it is understoodthat drive 28 can be of any suitable configuration for convertingrotational movement into linear movement, such as various cranks andother devices.

Piston 30 extends from wobble plate 48 and into axial bore 40 throughseal 36. Upstream end 50 of piston 30 is connected to wobble plate 48and downstream end 52 of piston 30 is disposed within cylinder 34.Piston 30 is tightly toleranced to cylinder 34 such that fluid isprevented from leaking upstream around downstream end 52 of piston 30.Piston 30 is driven in a linear, reciprocating manner by wobble plate 48to draw fluid into cylinder 34 through intake channel 44 and dispensethe fluid downstream through exit channel 24 and nozzle 22. Piston 30can be made of any suitable material for driving fluid from reservoir 14to nozzle 22, such as carbide, among others. Cylinder 34 can similarlybe made of carbide, among others.

Check valve 32 is disposed within pump body 26 at a downstream end ofaxial bore 40. Cage 54 is disposed within axial bore 40 between spraytip 16 and cylinder 34. In some examples, spray tip 16 secures cage 54against cylinder 34 such that check valve 32 is retained within housingby spray tip 16. Ball 56 is disposed within cage 54, and spring 58 isdisposed within cage 54 and biases ball 56 towards a closed position,where ball 56 abuts a downstream end of cylinder 34. Cylinder 34 thusprovides the seat of check valve 32. While check valve 32 is describedas including ball 56, it is understood that check valve can include anymovable valve member suitable for creating a seal with cylinder 34 whenin the closed position.

During operation, motor 18 is activated and rotatably drives gear 46.Gear 46 rotates and drives wobble plate 48, which in turn converts therotary motion of gear 46 into linear, reciprocating motion of piston 30,such that piston 30 is driven through one or more pump cycles. Duringthe pump cycle, piston 30 is drawn in a rearward direction through asuction stroke to draw the fluid into cylinder 34, and then piston 30 isdriven in a forward direction through a pressure stoke to drive thefluid out of cylinder 34 and to nozzle 22.

During the suction stroke, piston 30 is drawn in the rearward directioncreating a vacuum within cylinder 34 between check valve 32 anddownstream end 52 of piston 30. When downstream end 52 of piston 30passes intake channel 44, the vacuum draws the fluid from reservoir 14into cylinder 34.

After completing the suction stroke, piston 30 is driven in the forwarddirection and through the pressure stroke. As piston 30 is driven in theforward direction, the pressure builds in the fluid within cylinder 34.The pressure continue to build until the pressure overcomes the forcespring 58 exerts on ball 56, such that the pressure of the fluid unseatsball 56 from cylinder 34 causing ball 56 to shift from the closedposition to an open position. With ball 56 unseated from cylinder 34 andin the open position, the fluid flows out of axial bore 40 through checkvalve 32, and flows to nozzle 22 through exit channel 24. As such, thefluid, which is typically noncompressible, exerts the force required toovercome the force exerted on ball 56 by spring 58, such that the fluiddrives ball 56 from the closed position to the open position.

Prior to dispensing fluid, pump 20 is primed with the fluid fromreservoir 14. Prior to priming, cylinder 34 is typically filled with airbetween check valve 32 and downstream end 52 of piston 30. During thepressure stroke, the air, which has little momentum and is compressible,is compressed between piston 30 and check valve 32 and may not createsufficient pressure to displace ball 56 from cylinder 34, such that ball56 remains in the closed position and the air remains within cylinder 34between ball 56 and downstream end 52.

To facilitate priming, piston 30 is dimensioned and driven such thatdownstream end 52 of piston 30 impacts ball 56 when ball 56 is seated oncylinder 34. Downstream end 52 of piston 30 impacting ball 56 unseatsball 56 from cylinder 34, providing a flowpath around ball 56 for theair disposed within cylinder 34 to exit cylinder 34 through check valve32. With the air purged from cylinder 34, a sufficient vacuum can becreated during the suction stroke to draw fluid into cylinder 34 fromreservoir 14. With pump 20 primed, the fluid from reservoir 14 is drawninto and driven out of cylinder 34 during the pump cycle. Piston 30 canbe configured to not impact ball 56 except during a priming stroke, asthe pressure and momentum of the fluid from reservoir 14 unseats ball 56before downstream end 52 of piston 30 reaches the seated position ofball 56.

Pump 20 provides significant advantages. Downstream end 52 of piston 30impacts and unseats ball 56 during a priming stroke, facilitatingquicker and more efficient priming of sprayer 10. Piston 30automatically knocks ball 56 off of cylinder 34, which eliminates theneed for a user to manually knock ball. For example, paint can drybetween ball 56 and cylinder 34 causing ball 56 to stick to cylinder 34.Piston 30 can break the connection created by the dried paint byimpacting ball 56 and driving ball 56 off of cylinder 34. Downstream end52 impacting ball 56 also simplifies sprayer 10 by eliminatingadditional, separate components required to knock ball 56 off ofcylinder 34. Further, downstream end 52 impacting ball 56 provides for aquicker and more efficient spraying process, as piston 30 knocks ball 56off of the seat without the user having to disassemble sprayer 10, knockball 56 off of the seat, and reassemble sprayer 10 before use.

FIG. 2A is a front isometric view of pump 20. FIG. 2B is a rearisometric view of pump 20. FIGS. 2A and 2B will be discussed together.Pump body 26, drive 28, check valve 32 a, piston 30 a, piston 30 b, seal36 a, seal 36 b, retainer 60 b and retainer 60 c of pump 20 are shown.Cylinder housings 38 a-38 c of pump body 26 are shown. Drive 28 includesgear 46 and wobble plate 48.

Drive 28 is mounted on pump body 26, with gear 46 connected to anddriving wobble plate 48. Pistons 30 a-30 c (piston 30 c shown in FIG.3B) extend from wobble plate 48 into cylinder housings 38 a-38 c,respectively. Retainer 60 b is attached to a downstream end of cylinderhousing 38 b and retains check valve 32 b (shown in FIG. 3B) withincylinder housing 38 b. Similarly, retainer 60 c is attached to adownstream end of cylinder housing 38 c and retains check valve 32 c(shown in FIG. 3C) within cylinder housing 38 c. Retainer 60 b andretainer 60 c can be secured to cylinder housings 38 b and 38 c,respectively, in any suitable manner. For example, retainer 60 b can besecured to cylinder housing 38 b by interfacing threading on retainer 60b and cylinder housing 38 b. Similarly, retainer 60 c can be secured tocylinder 34 housing 12 c by interfaced threading on retainer 60 c andcylinder housing 38 c. Cylinder housing 38 a is configured to receive aspray tip, such as spray tip 16 (shown in FIG. 1B), to retain checkvalve 32 a within cylinder housing 38 a. The spray tip can be secured tocylinder housing 38 a in any desired manner, such as by interfacedthreading on the spray tip and cylinder housing 38 a.

Seals 36 a-36 c are disposed at an upstream end of cylinder housings 38a-38 c, respectively. Pistons 30 a-30 c extend into cylinder housings 38a-38 c through seals 36 a-36 c. Seals 36 a-36 c are configured toprevent fluid from leaking out of the upstream ends of cylinder housings38 a-38 c during operation. Seals 36 a-36 c can be of any suitableconfiguration for sealing the upstream end of cylinder housings 38 a-38c. In some examples, seals 36 a-36 c can be u-cup seals containingpre-rolled o-rings.

During operation, gear 46 is rotationally driven, and gear 46 driveswobble plate 48. Wobble plate 48 drives pistons 30 a-30 c in a linear,reciprocating manner. Pistons 30 a-30 c draw fluid into cylinderhousings 38 a-38 c, respectively, and drive the fluid downstream out ofcylinder housing 38 a. For example, wobble plate 48 can pull piston 30 bin the upstream direction, causing piston 30 b to enter a suction strokeand to draw fluid into cylinder housing 38 b. Wobble plate 48 can thenpush piston 30 b in the downstream direction, whereby piston 30 b ejectsthe fluid from cylinder housing 38 b. The fluid exits cylinder housing38 b and flows to cylinder housing 38 a through internal flowpaths(discussed in more detail in FIGS. 3A-3B) in pump body 26. The fluid isprovided downstream from cylinder housing 38 a to a spray nozzle, suchas nozzle 22 (best seen in FIG. 1B), where the fluid can be applied to asurface. Similarly, piston 30 c can draw fluid into cylinder housing 38c and eject the fluid such that the fluid flows from cylinder housing 38c to cylinder housing 38 a through internal flowpaths in pump body 26.Piston 30 a is configured to draw fluid directly to cylinder housing 38a and to drive the fluid downstream out of cylinder housing 38 a to thespray nozzle. The fluid drawn into pump body 26 by each of pistons 30a-30 c can thus be output through a common exit port. In some examples,the common exit port can be cylinder housing 38 a.

FIG. 3A is a cross-sectional view of pump 20 taken along line A-A inFIG. 2A. FIG. 3B is a cross-sectional view of pump 20 taken along lineB-B in FIG. 2B. FIG. 3C is an enhanced view of detail Z in FIG. 3B.FIGS. 3A-3C will be discussed together. Pump 20 includes pump body 26,drive 28, pistons 30 a-30 c (collectively “pistons 30”), check valves 32a-32 c (collectively “check valves 32”), cylinders 34 a-34 c(collectively “cylinders 34”), seals 36 a-36 c (collectively “seals36”), and retainers 60 b-60 c (collectively “retainers 60”). Pump body26 includes cylinder housings 38 a-38 c (collectively “cylinder housings38”), axial bores 40 a-40 c (collectively “axial bores 40”), radialbores 42 a-42 c (collectively “radial bores 42”), inlet channels 44(only one of which is shown), and intersection point 62. Drive 28includes gear 46 and wobble plate 48. Pistons 30 a-30 c respectivelyinclude upstream ends 50 a-50 c (collectively “upstream ends 50”) anddownstream ends 52 a-52 c (collectively “downstream ends 52”). Checkvalves 32 a-32 c respectively include cages 54 a-54 c (collectively“cages 54”), balls 56 a-56 c (collectively “balls 56”), and springs 58a-58 c (collectively “springs 58”). Cylinders 34 a-34 c respectivelyinclude downstream faces 64 a-64 c (collectively “downstream faces 64”),and downstream faces 64 a-64 c respectively include sealing lips 66 a-66c (only sealing lip 66 b is shown).

Cylinder housings 38 form portions of pump body 26 through which fluidis pumped. Axial bores 40 extend through cylinder housings 38, andcylinders 34 are disposed in cylinder housings 38 within axial bores 40.Radial bores 42 extend between axial bores 40 and intersection point 62.In some examples, radial bores 42 extend into axial bores 40 at alocation downstream of cylinders 34. Radial bores 42 provide passagewaysthrough pump body 26 that fluidly connect axial bores 40 to providefluid to a single exit port, such as through spray tip 16 (shown in FIG.1B). In some examples, cylinders 34 can be integrally retained withincylinder housings 38. For example, cylinder housings 38 can be formedaround cylinders 34, such as by insert molding. Cylinders 34 are shownas unitary parts. It is understood, however, that cylinders 34 can beformed from one or more components. For example, cylinders 34 caninclude a downstream portion and an upstream portion that are formedseparately. In some examples, the upstream portion and the downstreamportion are formed from different materials. In other examples, theupstream portion and the downstream portion can be formed from the samematerial. In one example where cylinders 34 are formed of multiplecomponents, the downstream portion can form the seat of check valves 32,and the upstream portion can be disposed within axial bores 40. Theupstream portion and the downstream portion can be formed integrallywithin pump body 26, can be separate from pump body 26, can be removablefrom pump body 26, or can be some combination thereof.

Intake channel 44 extends through pump body 26 to axial bore 40 a and isconfigured to supply fluid to axial bore 40 a from a fluid source, suchas reservoir 14 (shown in FIGS. 1A-1B). It is understood that pump body26 can include one or more additional inlet channels (not shown)extending between the fluid source and axial bore 40 b and axial bore 40c. For example, the additional inlet channels can extend to axial bore40 b and axial bore 40 c independent of intake channel 44. In someexamples, the additional inlet channels can extend to axial bore 40 band axial bore 40 c from intake channel 44, such that the additionalinlet channels branch from intake channel 44.

Drive 28 is mounted to pump body 26. Gear 46 is attached to and powerswobble drive 28. Gear 46 is configured for rotation, and wobble plate 48is configured to convert the rotational motion of gear 46 into linear,reciprocal motion of pistons 30. Pistons 30 are attached to wobble plate48 and extend into axial bores 40. Upstream ends 50 of pistons 30 areattached to wobble drive 28, and downstream ends 52 of pistons 30 aredisposed within cylinders 34. Seals 36 are disposed at an upstream endof axial bores 40, and seals 36 extend around pistons 30. Seals 36 areconfigured to prevent fluid from leaking out the upstream ends of axialbores 40, and seals 36 can be of any suitable configuration for sealingaxial bores 40. For example, seals 36 can be u-cup seals havingpre-rolled o-rings.

Check valves 32 are disposed within axial bores 40 downstream ofcylinders 34. Retainer 60 b is disposed at a downstream end of axialbore 40 b and at least partially seals axial bore 40 b. Morespecifically, check valve 32 b is retained within axial bore 40 b byretainer 60 b. Similarly, retainer 60 c is disposed at a downstream endof axial bore 40 c and at least partially seals axial bore 40 c, andcheck valve 32 c is retained within axial bore 40 c by retainer 60 c. Insome examples, retainer 60 b and retainer 60 c include threadingconfigured to mate with threading on axial bore 40 b and axial bore 40c, respectively. It is understood, however, that retainer 60 b andretainer 60 c can be secured within axial bore 40 b and axial bore 40 cin any suitable manner, such as by friction fitting or welding. In someexamples, check valve 32 a is retained within axial bore 40 a by a spraytip for a sprayer, such as spray tip 16 (shown in FIG. 1B).

Cages 54 of check valves 32 are disposed in axial bores 40 adjacent adownstream face of cylinders 34. Springs 58 are disposed in cages 54 andare configured to bias balls 56 towards the closed position. Balls 56are at least partially disposed in cages 54 and abut the downstreamfaces 64 of cylinders 34 when in a closed position. More specifically,balls 56 can abut sealing lips 66 of downstream faces 64 when in theclosed position. Sealing lips 66 can is contoured to match a contour ofballs 56, thereby facilitating sealing of balls 56 on downstream faces64. Sealing lips 66 can be tapered, concave, or of any other desiredconfiguration for facilitating sealing with balls 56. With balls 56 inthe closed position, check valves 32 prevent fluid from flowingdownstream from cylinders 34. In the closed position, balls 56 can atleast partially extend into cylinders 34, such that at least a portionof each ball 56 is disposed upstream of the downstream face of anassociated cylinder 34.

The pumping cycles of pistons 30 a-30 c, which include a suction strokeand a pumping stoke, are substantially similar, and will be discussedgenerally. During operation, gear 46 is rotatably driven and driveswobble plate 48, which in turn converts the rotary motion of gear 46into linear reciprocating motion of pistons 30. In a suction stoke,pistons 30 are drawn upstream through cylinders 34, creating a vacuumwithin cylinders 34 between check valves 32 and downstream ends 52 ofpistons 30. Pistons 30 are pulled in the upstream direction untildownstream end 52 passes a channel providing fluid to that cylinder 34,whereupon the vacuum draws fluid into cylinder 34.

After completing the suction stroke, pistons 30 enter the pressurestroke, where wobble plate 48 drives pistons 30 in the downstreamdirection through cylinders 34. As pistons 30 are driven in thedownstream direction, the pressure builds in the fluid within cylinders34 until the pressure overcomes the force of springs 58, unseating balls56 from the downstream faces of cylinders 34. With balls 56 unseatedfrom cylinders 34, the fluid flows out of cylinders 34 through checkvalves 32 and to a dispensing nozzle, such as nozzle 22 (shown in FIGS.1A-1B).

As shown specifically in FIG. 3B, fluid flowing out of cylinder 34 bthrough check valve 32 b enters radial bore 42 b. Similarly, the fluidflowing out of cylinder 34 c through check valve 32 c enters radial bore42 c. The fluid flows through radial bore 42 b or radial bore 42 c tointersection point 62. From intersection point 62, the fluid flowsthrough radial bore 42 a and is provided to axial bore 40 a, at alocation downstream of cylinder 34 a. Providing the fluid to axial bore40 a at a location downstream of cylinder 34 a prevents check valve 32 afrom inhibiting the flow of fluid from either axial bore 40 b or axialbore 40 c.

Prior to dispensing fluid, pump 20 is primed with the fluid to besprayed. Prior to priming, cylinders 34 are filled with air, which caninhibit the proper uptake of fluid into cylinders 34 such that pump 20will not be properly primed. As pistons 30 are driven in the forwarddirection through the priming stroke, the air is compressed withincylinders 34 between balls 56 and downstream ends 52 of pistons 30. Thepressure generated by compressing the air in cylinders 34 may fail torise to a sufficient level to overcome the force of springs 58maintaining balls 56 in the closed position. As such, balls 56 may notunseat from sealing lips 66 due to the air pressure alone. In somecases, balls 56 can adhere to sealing lips 66 due to the fluid beingpumped, such as paint, drying between balls 56 and sealing lips 66. Toensure efficient priming, pistons 30 are dimensioned to impact anddisplace ball 56, or any other valve element of check valves 32, fromdownstream face 64 as pistons 30 proceed forward through a primingstroke. Displacing balls 56 from sealing lips 66 allows the air to exitcylinders 34 through check valves 32. After pump 20 is primed, thepressure generated by the fluid between pistons 30 and check valves 32is sufficient to unseat balls 56. As such, pistons 30 can be configuredto impact and unseat balls 56 only during priming. Having pistons 30impact balls 56 only during priming minimizes any wear on balls 56 dueto contact with pistons 30.

The priming strokes of pistons 30 a-30 c are substantially similar, andthe priming stroke of piston 30 b will be discussed in more detail. Apriming stroke is a pressure stroke that occurs prior to pump 20 beingprimed. In FIG. 3C, piston 30 b is shown at a forward extent of apriming stroke and is in contact with ball 56 b. During the primingstroke, piston 30 b is driven forward and downstream end 52 b impactsball 56 b, displacing ball 56 b from sealing lip 66 b of cylinder 34 b.Displacing ball 56 b from sealing lip 66 b of cylinder 34 b opens a gapbetween ball 56 b and sealing lip 66 b through which the air can beejected from cylinder 34 b. After completing the priming stroke, piston30 b reverses stroke direction and begins the suction stroke. Ball 56 bcan reseat on sealing lip 66 b and the vacuum can be created withincylinder 34 b, facilitating priming of pump 20.

In some examples, downstream ends 52 of pistons 30 remains upstream ofdownstream faces 64 of cylinders 34 when pistons 30 is in theforward-most position of the priming cycle. With downstream ends 52upstream of downstream faces 64, balls 56 are positioned on downstreamfaces 64 such that a portion of ball extends into cylinders 34, sodownstream faces 64 of pistons 30 can impact and unseat balls 56 fromcylinders 34 when pistons 30 are in the forward-most position. In someexamples, downstream ends 52 of pistons 30 are aligned with downstreamfaces 64 of cylinders 34 when pistons 30 are in the forward-mostposition. In some other examples, downstream ends 52 of pistons 30project beyond downstream faces 64 of cylinders 34 and into check valves32 when pistons 30 are in the forward-most position. In each example,downstream ends 52 are configured to impact and unseat balls 56 from theclosed position during the priming cycle.

Pump 20 provides significant advantages. Pistons 30 automatically knockballs 56, or any valve member of a different configuration, out of aclosed position during priming. Automatically knocking balls 56 out ofthe closed position eliminates additional components that were requiredto knock balls 56 from the closed position, thereby simplifying pump 20and providing for quicker, more efficient priming. Furthermore,configuring pistons 30 to knock balls 56 during priming but not duringpumping prevents excessive wear on balls 56 from contact with downstreamends 52 of pistons 30, thereby providing a longer lifespan forcomponents of pump 20.

FIG. 4A is an isometric view of check valve 32. FIG. 4B is an explodedview of check valve 32. FIGS. 4A and 4B will be discussed together.Check valve 32 includes cage 54, ball 56, and spring 58. Cage 54includes ligaments 68. Spring 58 is disposed within cage 54 and isconfigured to bias ball 56 out of cage 54. Ligaments 68 provide supportfor cage 54 and retain spring 58 within cage 54. Ligaments 68 furtherdefine gaps extending between ligaments 68 through which fluid can exitcheck valve 32. Cage 54 serves as a downstream stop for ball 56 suchthat ball 56 can displace into cage 54 a set distance before cage 54prevents further progress of ball 56. With ball 56 displaced into cage54, fluid can flow around ball 56, into cage 54, and can exit cage 54and flow downstream through the gaps between ligaments 68.

FIG. 5 is a flow chart of method 100 of priming a pump. In step 102, apiston, such as pistons 30 (best seen in FIGS. 3A-3B) is driven througha priming stroke. For example, rotary motion from a motor, such as motor18 (shown in FIG. 1B), can be converted to linear, reciprocal motion ofthe piston by a drive, such as drive 28 (best seen in FIGS. 3A-3B). Thepriming stroke is a pressure stroke of the piston that occurs prior tothe pump being primed.

In step 104, a downstream end of the piston impacts a valve member, suchas balls 56 (best seen in FIGS. 3A-3B), of a check valve, such as checkvalves 32 (best seen in FIGS. 3A-3B), and drives the valve member from aclosed position to an open position. Driving the valve member to theopen position provides an ejection flowpath through the check valvethrough which any air trapped between the check valve and the piston canbe ejected.

In step 106, the piston is pulled through a suction stroke. With the airejected from the pump, a vacuum can form between the piston and thecheck valve during the suction stroke. When the downstream end of thepiston passes an intake, the vacuum draws pumped fluid into the chamberbetween the check valve and the piston. The pump is thus primed andready to dispense fluid. In one example, the pump is a pump for asprayer, such as sprayer 10, and the fluid can be applied to a surfacewith the sprayer.

While the invention has been described with reference to an exemplaryembodiment(s), it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment(s) disclosed, but that theinvention will include all embodiments falling within the scope of theappended claims.

1. A pump for a fluid sprayer, the pump comprising: a first pistondisposed within a first axial bore of a pump body, the first pistonhaving a downstream end movable within the first axial bore; and a firstcheck valve disposed at an exit of the first axial bore, the first checkvalve including a first valve member; wherein the downstream end of thefirst piston is configured to impact the first valve member to drive thefirst valve member from a closed position to an open position.
 2. Thepump of claim 1, wherein the downstream end is configured to impact anddisplace the first valve member during a priming stroke of the firstpiston.
 3. The pump of claim 2, wherein: the first piston is drawnrearward through the first axial bore during a suction stroke and isconfigured to draw a fluid into the first axial bore during the suctionstroke; and the first piston is driven forward through the first axialbore during a pressure stroke and is configured build a pressure in thefluid and drive the fluid downstream out of the first axial bore throughthe first check valve during the pressure stroke.
 4. The pump of claim3, wherein the first piston is configured to not impact the first valvemember during both the suction stroke and the pressure stroke.
 5. Thepump of claim 4, wherein the first piston is configured to build a fluidpressure between the downstream end of the first piston and the firstvalve member during the pressure stroke of the first piston, the fluidpressure configured to drive the valve member from the closed positionto the open position during the pressure stroke of the first piston. 6.The pump of claim 1, further comprising: a first cylinder disposedwithin the first axial bore, wherein the first piston extends into thefirst cylinder, and wherein a downstream face of the first cylinderforms a seat for the first valve member such that the first valve membercontacts the downstream face when the first valve member is in theclosed position.
 7. The pump of claim 6, wherein the downstream end ofthe first piston is aligned with the downstream face of the firstcylinder with the first piston in a forward-most position.
 8. The pumpof claim 6, wherein the downstream end of the first piston is disposedwithin the first cylinder upstream of the downstream face of the firstcylinder with the piston in a forward-most position.
 9. The pump ofclaim 6, wherein the first valve member is a ball.
 10. The pump of claim9, wherein the first check valve further comprises: a cage, the ball atleast partially disposed within the cage; and a spring disposed withinthe cage and configured to urge the ball towards the closed position.11. The pump of claim 9, wherein the downstream face of the firstcylinder includes a sealing lip configured to mate with a curvature ofthe ball such that a portion of the ball extends into the cylinder. 12.The pump of claim 1, further comprising: a second piston disposed withina second axial bore of the pump body, the second piston having adownstream end movable within the second axial bore; a second checkvalve disposed at an exit of the second axial bore, the second checkvalve including a second valve member; a second cylinder disposed withinthe second axial bore, wherein the second piston extends into the secondcylinder, and wherein a downstream face of the second cylinder forms aseat for the second valve member such that the second valve membercontacts the downstream face when the second valve member is in theclosed position; and a first valve retainer secured within a downstreamend of the second axial bore and configured to retain the second checkvalve within the second axial bore; wherein the downstream end of thesecond piston is configured to impact the second valve member to drivethe second valve member from a closed position to an open positionduring a priming stroke of the second valve member; wherein the secondpiston is drawn upstream through the second cylinder during a suctionstroke and is configured to draw a fluid into the second cylinder duringthe suction stroke; and wherein the second piston is driven downstreamthrough the second cylinder during a pressure stroke and is configuredbuild a pressure in the fluid and drive the fluid downstream out of thesecond cylinder through the second check valve during the pressurestroke.
 13. A handheld sprayer comprising: a sprayer body, the sprayerbody including a handle configured to support the sprayer body; a spraytip attached to the sprayer body and configured to spray a fluid; areservoir connected to the sprayer body and configured to store a supplyof the fluid; and a pump disposed within the sprayer body and configuredto draw the fluid from the reservoir and drive the fluid downstream tothe spray tip, the pump comprising: a pump body mounted within thesprayer body, the pump body including an axial bore and an inlet channelconfigured to fluidly connect the axial bore and the reservoir; a pistonextending into the axial bore, the piston having an upstream endconnected to a drive and a downstream end configured to reciprocatewithin the axial bore, the piston configured to draw the fluid from thereservoir during a suction stroke and to drive the fluid downstream tothe spray tip during a pressure stroke; and a check valve disposedwithin the axial bore downstream of the piston, the check valveincluding a valve member; wherein the downstream end of the piston isconfigured to impact the valve member and drive the valve member from aclosed position to an open position during a priming stroke of thepiston.
 14. The handheld sprayer of claim 13, wherein a portion of theaxial bore disposed between the downstream end of the piston and thevalve member is devoid of the fluid during the priming stroke.
 15. Thehandheld sprayer of claim 14, wherein: the piston is drawn upstreamthrough the first axial bore by the drive during the suction stroke, andthe piston is configured to draw the fluid from the reservoir and intothe axial bore during the suction stroke; the piston is drivendownstream through the axial bore by the drive during the pressurestroke, and the piston is configured to drive the fluid downstream fromthe axial bore through the check valve during the pressure stroke; andthe downstream end is configured to not contact the valve member duringthe suction stroke and the pressure stroke.
 16. The handheld sprayer ofclaim 15, further comprising: a cylinder disposed within the at leastone axial bore, wherein the piston extends into the cylinder, andwherein a downstream face of the cylinder forms a seat for the valvemember such that the valve member contacts the downstream face when thevalve member is in the closed position.
 17. The handheld sprayer ofclaim 16, wherein the piston is configured to build a fluid pressurebetween the downstream end of the piston and the valve member during thepressure stroke such that the fluid pressure drives the valve memberfrom the closed position to the open position during the pressurestroke.
 18. The handheld sprayer of claim 16, wherein the downstream endof the piston is configured to be one of aligned with the downstreamface of the cylinder when the piston is in a forward-most position anddisposed upstream of the downstream face of the cylinder when the pistonis in the forward-most position.
 19. The handheld sprayer of claim 13,wherein the drive comprises: a gear configured to be rotatably driven bya motor mounted in the housing; and a wobble drive powered by the gearand configured to convert the rotational movement from the gear to alinear movement of the piston.
 20. A method of priming a pump, themethod comprising: driving a piston through a priming stroke; impactinga valve member with the piston to drive the valve member from a closedposition to an open position; pulling the piston through a suction stoketo draw fluid downstream from a reservoir and prime the pump.